67 



40° C. tlie presentation-time increases witli a longer 

 duration of pieliminaiy warming, and the more so when 

 the température is higher. Thus at 40° C. the presenta- 

 tion-time could only be determined after 1 hours' warming. 



Thèse results for the températures 30° C, 35° C, 37° C. 

 and 38° C. are represented graphically in Fig. 5. The 

 diagrams, given there, show very clearly the différence in 

 behaviour between the presentation-time at 30° C. and at 

 higher températures. The curve at 30° C. slopes down- 

 wards, those at higher températures upwards. The mea- 

 ning of this phenomenon will be discussed in Chapter III. 



The widely divergent values of the presentation-time 

 make it impossible to give a diagram in which full jus- 

 tice is done to différences of some 10 seconds, while the 

 highest values found are also represented. Therefore such 

 a scale has been chosen in drawing Fig. 6 and 7, that 

 the small différences can bc seen, but some of the highest 

 values are outside the diagram. 



In Fig. 6, drawn after van Iterson '; the abscissae- 

 axis has been taken as temperature-axis. graduait-d tn 

 1° C, and the ordinate-axis has been taken to represent 

 the presentation-time, graduated to 2 minutes. 



From 0° C. to 25° C. we find only one value of the 

 presentatiun-time at each température, from 30° C. upwards 

 we find more values marked 1 to 6; the littlc crosses 

 numbered 1 are the values fuund after 1 hours'jprelimlnary 

 warming, those numbered 2 after 2 hours', those num- 

 bered 3 after 4 hours', those numbered 4 after 6 hours', 

 those numbered 5 after 12 hours', those numbered 6 after 

 24 hours'. The broad black line represents the presentation- 

 time after 1 hours' preliminary warming, the thin line 

 starting from 25° C. the same after 12 hours' preliminary 



1) G. van Iterson Jr. Mav lOlO. 



